#define _CRT_SECURE_NO_WARNINGS 1

#include<iostream>
#include<vector>
#include<queue>
using namespace std;

struct TreeNode 
{
    int val;
    TreeNode *left;
    TreeNode *right;
    TreeNode() : val(0), left(nullptr), right(nullptr) {}
    TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
    TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
};
 
class Solution
{
public:
    vector<double> averageOfLevels(TreeNode* root)
    {
        queue<TreeNode*> q;
        q.push(root);
        vector<double> ret;

        while (!q.empty())
        {
            double sum = 0;
            int size = q.size();
            int n = size;
            while (size--)
            {
                TreeNode* front = q.front();
                q.pop();
                sum += front->val;
                if (front->left) q.push(front->left);
                if (front->right) q.push(front->right);
            }
            ret.push_back(sum / n);
        }
        return ret;
    }
};

class Solution
{
public:
    int minDepth(TreeNode* root)
    {
        if (root == nullptr) return 0;

        if (root->left == nullptr)
            return minDepth(root->right) + 1;

        if (root->right == nullptr)
            return minDepth(root->left) + 1;

        return min(minDepth(root->left), minDepth(root->right)) + 1;
    }
};